Weaning transitions

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Most dairy producers now do a great job feeding calves. Colostrum management has improved drastically, and almost everyone feeds some version of an accelerated milk-feeding program. As a result, calves grow much faster before weaning than in the past, and wet calf mortality is low on most farms. However, there is a dark side to accelerated growth. It is often harder for calves to make the weaning transition. Why is that?

Dr. James Drackley presented on this topic at the American Association of Bovine Practitioners annual meeting. Drackley listed six reasons for poor weaning transition: weaning too early, weaning too abruptly, feeding too much forage, poor starter quality, poor water management and stacking stressors at weaning.

First, weaning too early — for example, at 6 weeks instead of 8 weeks — can easily cause an energy deficit of 50%. Early-weaned calves may experience severe energy deficits because they are not eating enough starter when weaning starts. Two pounds of a typical starter will provide only enough energy to meet maintenance for a 180-pound calf. Thus, to maintain growth, calves need to eat substantially more than 2 pounds per day. In fact, there is a strong relationship between starter intake before weaning and rate of gain after weaning. Indeed, poor starter intake is probably the most common reason for failure to successfully transition to the post-weaning period. Energy deficits not only reduce growth but can result in a whole variety of health problems, including pneumonia and diarrhea.

Weaning too abruptly can result in a similar energy deficit because calves that are fed adequate or large amounts of milk may be reluctant to eat sufficient starter due to the insufficient amount of time for the calf to adjust starter intake. Many producers now do two- or three-step reductions in milk quantity for this reason.

Poor starter quality may include too much starch, poor palatability or poor particle size. Textured starters are preferred to pelleted starters because calves tend to eat more of them. Poor starter quality can mean feeding errors, like not removing spoiled feed, for example. Starters with high starch levels, around 40% on a dry matter basis, may result in significant rumen acidosis. Rumen acidosis can lead to increased intestinal permeability, which has been called leaky gut syndrome. This syndrome often leads to respiratory disease. Acidotic calves often have diarrhea and may also be more susceptible to parasitic and bacterial enteritis. New starter formulations tend to have lower starch, higher sugars, and higher digestible and soluble fiber.

Water is critical for proper growth after weaning. Milk and milk replacers mostly bypass the rumen. Water is needed in the rumen, however, for microbial growth. For every 2.2 pounds of starter, calves need to consume about 1gallon of water. In fact, if one plots starter intake and water intake on a graph, the intake patterns of starter and water are almost identical. So, if your goal is for your calves to consume 4.4 pounds of starter at weaning, for example, you need to provide at least 2 gallons of water daily. Limiting water intake will limit starter intake. Dirty water can also reduce intake. Drackley suggested keeping feed and water buckets separated so that calves must pull their heads back through a hole and insert it into a different hole or slot to help reduce feed contamination of the water.

Feeding small amounts of forage can increase starter intake and feed efficiency. However, eating too much forage will decrease starter intake. If calves are fed free-choice forage, the amount they will eat will depend on what kind of forage is fed. Calves fed free-choice alfalfa hay will eat significantly more forage than calves fed straw or rye-grass hay, and such excess intake can significantly reduce starter intake. Drackley recommended that small amounts of grass hay or straw be fed to calves after weaning and alfalfa hay be limited up to at least 6 months of age.

Stressors mean things we do to calves that may cause stress at weaning time. Stressors can be prevented by avoiding vaccinations or other procedures during roughly the week before and the week after weaning. It also means avoiding mixing calves with other calves until after every calf has fully recovered from weaning and is eating starter well. Sometimes we might have to do one stressful procedure around weaning, but stacking just means doing more than one at, or nearly at, the same time. Try to avoid stressors if possible.

Successful transitions through weaning are critically important to keep calves healthy and achieve adequate growth in the post-weaning phase. By avoiding these six reasons for failure, you can help your calves do well.

Bennett is one of four dairy veterinarians at Northern Valley Dairy Production Medicine Center in Plainview, Minnesota. He also consults on dairy farms in other states. He and his wife, Pam, have four children. Jim can be reached at [email protected] with comments or questions.

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